24th Sep 2019, 1:21 pm | #41 |
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Re: Bush TV22 with TC184 B3 converter.
Hi Lloyd,
The CRT is the original Mullard MW22-16. Displays a very bright picture. DFWB. |
24th Sep 2019, 1:35 pm | #42 | |
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Re: Bush TV22 with TC184 B3 converter.
Quote:
Peter |
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24th Sep 2019, 2:55 pm | #43 |
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Re: Bush TV22 with TC184 B3 converter.
Hi Peter,
Boost capacitor C21. 4 microfarads was the value of the old boost capacitor and I've seen other TV22 receivers with this value for C21. DFWB. |
24th Sep 2019, 3:54 pm | #44 |
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Re: Bush TV22 with TC184 B3 converter.
Did some one say a while back to soak the over wind in WD40?
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24th Sep 2019, 5:22 pm | #45 |
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Re: Bush TV22 with TC184 B3 converter.
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25th Sep 2019, 12:18 am | #46 | |
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Re: Bush TV22 with TC184 B3 converter.
Quote:
Cheers Andy
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25th Sep 2019, 7:03 am | #47 | |
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Re: Bush TV22 with TC184 B3 converter.
Quote:
I only have a couple of misgivings, it appears that WD-40 is hygroscopic, see: http://worldphaco.com/uploads/THE_WD.pdf and pitch itself has a tacky surface. I prefer varnish (and I also coat my restored waxies with this) because dust doesn't stick to it after it dries. |
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25th Sep 2019, 4:54 pm | #48 |
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Re: Bush TV22 with TC184 B3 converter.
Because the Bush TV22 is becoming scarce I've found an alternative set to dump in the Biffa bin.
DFWB. |
25th Sep 2019, 6:20 pm | #49 |
Nonode
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Re: Bush TV22 with TC184 B3 converter.
I've got a couple of round Ekco's that can join it
Regards, Lloyd |
25th Sep 2019, 7:31 pm | #50 |
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Re: Bush TV22 with TC184 B3 converter.
David, I think that's great news! I might then be able to find a scrap chassis to fill my empty cabinet.
Peter |
25th Sep 2019, 8:16 pm | #51 |
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Re: Bush TV22 with TC184 B3 converter.
"I've got a couple of round Ekco's that can join it"
Hi Lloyd, I've got one round Ekco that should really be put in the bin, but that's not going to happen, it's gong to be fixed. "David, I think that's great news! I might then be able to find a scrap chassis to fill my empty cabinet." Hi Peter, you've got an empty TV22 cabinet? Meanwhile, my TV22 has been on for more than three hours and is working fine. But, it ain't half hot! DFWB. |
25th Sep 2019, 8:31 pm | #52 |
Nonode
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Re: Bush TV22 with TC184 B3 converter.
Haha, yes, they must be fixed up, not binned! I'm getting there slowly with mine, it certainly is sounding good now!
Those TV22's do get a bit toasty, I had one running for a whole 8 hours at a vintage show once, and because I knew it had a bit of a tendency to get hot I removed the screening can from the LOPT, and fitted a 12V computer fan on the back cover in the ventilation slots, that kept it happy for the day, and it was still working well at the end of the show, sadly that set developed the shorted primary much later on, and is waiting for me to do something about it. As for empty cabinets, I have a TV62 cabinet in the lock up! Regards, Lloyd |
25th Sep 2019, 9:10 pm | #53 |
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Re: Bush TV22 with TC184 B3 converter.
No, not a TV22 but a Philco People's Set. If memory serves me correctly it's a 444.
I've now tidied up my TV22 LOPT and put the metalwork around it but I'm tempted to leave the lid off. Peter Last edited by peter_scott; 25th Sep 2019 at 9:20 pm. |
25th Sep 2019, 9:29 pm | #54 | |
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Re: Bush TV22 with TC184 B3 converter.
Quote:
I have never liked the heat generated by the PL36 & PZ30 in such an enclosed space, probably the reason all the sets I have seen have melted pitch from the LOPT around it's base, and some have dripped on to the receiver chassis! Mark |
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25th Sep 2019, 10:07 pm | #55 |
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Re: Bush TV22 with TC184 B3 converter.
Yes, with no surrounding metalwork it ran quite reasonably "cool", well warm anyway. Maybe I'll take the rear metalwork away too leaving the front/side to give better support to EHT lead.
Peter |
25th Sep 2019, 10:18 pm | #56 | |
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Re: Bush TV22 with TC184 B3 converter.
Quote:
Maybe they should have put a slot in the back of these sets for a slice of toast. |
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25th Sep 2019, 10:29 pm | #57 |
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Re: Bush TV22 with TC184 B3 converter.
Hi Peter,
Many years ago I bought a Peoples set which turned out to have been made up from various bits and pieces. The bakelite cabinet is slightly larger than the regular 444 and the chassis came out of a model 296 woodie. Getting back to the TV22. The interlace is not very good in my set, the problem being that there is line pairing irrespective of the frame hold setting. Also, the set needs frame flyback blanking. The coupling between the video amplifier does not maintain the DC component thus on scenes with low contrast the black level rises and the flyback lines become apparent. DFWB. |
26th Sep 2019, 8:29 am | #58 |
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Re: Bush TV22 with TC184 B3 converter.
I don't think this is correct. There is DC coupling in the TV22 all the way from the detector to the CRT's cathode, it (the DC component) is slightly divided down by the 47k and 270k resistor, only to about 270/(270 +47), so 85% of the original DC value is retained, which is more than adequate.
The reason why, on a TV-22 , or this type of design, the retrace blanking turns out to fail, is the nature of the RF modulation on the video carrier, not being stabilized/clamped. It is the consequence in some RF modulators of not clamping the DC axis of the sync tips (or black level) with respect to the RF carrier being modulated. So the effect of this is identical to having AC coupling in the video amplifier pathway, with no DC restorer and no DC coupling. I mentioned this elsewhere, where people were seeing a lot of retrace lines on the TV22, and on mine (standard without internal retrace blanking added) I don't see them. My modulators have proper video clamping at the modulator. Interestingly, in other video amp systems that are AC coupled, if they have a DC restorer at the CRT, it doesn't matter in those if the video signal in the RF modulator is not properly clamped, it makes no difference, even a poor modulator without clamping appears to work perfectly. So the Bush TV 22 is an excellent set to test the quality of the design of an RF modulator, if you see the retrace lines at times after the contrast and brightness controls are correctly set, the RF modulator in use has poor clamping and its design is sub-optimal. The original transmitted signals from the TV station of course always had this issue attended to, so there were no issues for TV's that used direct coupling from the detector to the CRT. Last edited by Argus25; 26th Sep 2019 at 8:34 am. |
26th Sep 2019, 10:32 am | #59 |
Octode
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Re: Bush TV22 with TC184 B3 converter.
Since the TV22 LOPT has been discussed in this thread, I'll drop in the detailed measurements I made of three of them a few years ago. I've since measured two more and they more or less agree with the table.
The TV22 and TV24 LOPTs are identical as far as I know, with minor component variations around them in the two sets. (There are two different methods of mounting them to the chassis - in both models - but that's not relevant here.) Ian |
26th Sep 2019, 6:47 pm | #60 | |
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Re: Bush TV22 with TC184 B3 converter.
Quote:
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